Mobile computers such as a laptop personal computer (laptop PC) and a tablet-type computer (tablet PC) are equipped with a rechargeable battery. Laptop PCs often include a battery pack that is detachable at a bay of a housing thereof, among which a thin mobile computer such as a laptop PC called Ultrabook® or a tablet PC often uses an internal battery stored in the housing.
Replacing of such an internal battery of a mobile computer needs to open a cover of the housing. In addition to the internal battery, some other electronic devices such as a processor and a main memory may be replaced while letting the cover of the housing open. Even after shifting a mobile computer to a soft-off state or a power-off state (S5 state of ACPI) using a power button or a GUI thereof, electricity is still supplied from an AC/DC adapter or a battery to a device necessary to start up a power supply.
It is then necessary to, prior to opening of the housing for replacement of a component, remove the AC/DC adapter and then stop power supply from the battery to stop all power supplies other than a RTC, thus preventing damage due to short circuit. ACPI defines such a state as a mechanical-off state (G3 state). A mobile computer coming with a battery pack can easily shift to the G3 state by removing an AC/DC adapter and the battery pack therefrom.
On the other hand, in the case of a mobile computer coming with an internal battery, the internal battery cannot be removed without opening the housing. Then the mobile computer is powered on and a switch incorporated in the internal battery is turned off via a setup screen of the BIOS, thus shifting the mobile computer to a mechanical-off state. Japanese Patent application publication No. 2004-148724 discloses an image formation apparatus that is configured to shut down a power supply when the cover thereof is opened.